Hi there JustBreathe. Your post sounds a lot like how things started out with my now AH when we were your age. The only real difference is that I married mine and we have 2 children together and he has literally cratered our lives with addiction.
Have you heard of NarAnon? If not, I would encourage you to check out their online forums or go to an in person meeting. I think that support community is fantastic - it was a life saver for me.
If I could go back in time and have my 40 year old self meet my bright-eyed, happy go lucky, 21 year old self who was literally addicted the way you mention to my handsome husband who was also my best friend, I would tell her "RUN, RUN FAR AWAY and don't you look back - you'll thank me for it later". Of course, life doesn't work that way, and I have come to realize that wondering about the what if's (both future and present) only cause us to not sit and appreciate what is in front of us today. For today, it doesn't sound like what he is behaving like isn't even what you want, so why go and play roulette with something that has only showed you its true colors over and over?
I love the saying "when people show you who they are, believe them". Words are just that, WORDS. Actions - now that's where the rubber meets the road in my life now because for far too long, I believed the empty words and paid for it greatly.
Hugs and keep coming back.